It's amazing how much marketing can be done in 140 characters. Twitter offers promoted Tweets, promoted accounts and promoted trends, which allow brands to run product launch campaigns across the site or to target specific groups of users.

Even the simple cup of tea is getting the Twitter treatment. Tetley Tea has ramped up its presence on the micro-blogging site over the past year, using hashtags, promoted Tweets and targeting to add an extra layer of engagement to its marketing campaigns.

The brand's first big use of Twitter was to bolster its sponsorship of C5 Sunday afternoon family films. Viewers were encouraged to send in Tweets about the brand which were then displayed in the sponsorship idents (brand messages) around films.

Tetley marketing director Amy Holdsworth says the campaign was successful and received some 600 Tweets. "Our strategy is driving the salience of the brand – everyone knows us but we now need 'recency', keeping the brand in people's minds and talking to lots of people regularly. Social media gives us a really good opportunity to build the size and scale of communities cost effectively," she says.

Tetley has built up half a million likes on Facebook, though these are closed communities of friends and family. Twitter's open platform – where everyone can see what everyone else is saying - makes it ideal for marketing in the moment.

"You can join in people's conversations. If there's a Twitter conversation with people saying "ooh it's cold today," we can join in and say: "Warm yourself up with a nice cup of tea," says Holdsworth.

Twitter says that 40% of conversations on the platform during peak TV viewing time are about what's happening on TV screens, offering brands a strong opportunity to get their TV ads talked about.

Tetley ran an ad campaign over the summer featuring a Twitter hashtag as it sought to boost second screen conversations about the brand. "It is in the experimental stage," says Holdsworth. "We have got 85,000 Twitter followers engaging on a regular basis. We are constantly trying new things."

Brands can use the platform for free, building up followers and sending out Tweets. But the big opportunity for brands is in targeting specific groups of consumers. Paid-for campaigns can target users according to their interests, key words in their conversations and their gender.

Dara Nasr, Twitter's UK head of agency sales, says the site has 15 million active users in the UK, which is up 50% on last year. "It took us three years to serve a billion tweets. We are now doing it every two days. There are billions of conversations going on and that is an area brands can get involved in because it is the real-time pulse of the planet," he says.

He adds that promoted tweets can be particularly effective for promoting brand messages. They appear in the user's Twitter feed and can be targeted to different groups. The brand is charged "per engagement", which means when the user engages with the Tweet by retweeting it, marking it as a favourite or clicking on a link in the Tweet.

Promoted trends allow a brand to appear in the "trending" section on the left-hand side of the Twitter feed. This is powerful for new launches or significant activity and brands pay to appear in the trends section for 24 hours. Promoted accounts appear as suggestions of accounts to follow and are powerful for building up followers.

Price comparison site Confused.com has used Twitter in various ways. In one campaign it used promoted accounts to attract new followers, targeting students, newlyweds and mothers using "lookalike" targeting. This finds people who are "similar" to existing followers in interests or the people they follow. The campaign helped Confused.com boost its number of Twitter followers from 3,000 to 39,000.

Sharon Flaherty, Confused.com's head of content and PR, says: "Twitter delivers a lot of traffic to our website. If they don't become followers today, hopefully they will somewhere down the line. We have also reduced our reliance on email. Two years ago my main source of traffic to Confused.com came from the emailed newsletter. Now we have grown our traffic from other referral sites like Twitter."

But some brands are still wary of getting involved with Twitter after a number of campaigns seemed to backfire. Last year, Waitrose asked users to Tweet why they shopped at the store and received a barrage of sarcastic replies. This is a marketing platform that asks people to answer back.

Brands are still experimenting with Twitter, but it is fast becoming an indispensable platform for marketing. As Confused.com's Sharon Flaherty says: "Social media is a growth area but we are not expecting it to be a revenue generator overnight. It is about being smart in how you speak to customers. It is another avenue to give us a face and a personality and allow customers to speak to us."